Apparatus for altering weight profile of picker laps

ABSTRACT

By adjusting the flow of air into the beater chamber of a picker lapper so that more air is delivered to the sidewall sections than to the center of the chamber, laps of textile fibers are produced which are heavier in the center sections than at their edge sections.

United States Patent 91 McLaughlin et al.

[ Oct. 16, 1973 APPARATUS FOR ALTERING WEIGHT PROFILE OF PICKER LAPS Inventors: George B. McLaughlin, Windham;

George A. Wilcox, Willimantic, both ofConrn H Assigneez The Kendall Company, Walpole,

M ser.

Filed: Apr. 14, 1972 Appl. No.: 243,983

US. Cl. 19/89, 19/95 Int. Cl D0lg 9/04 Field of Search 19/88, 89, 155, 156-156.4,

References Cited UNITED STATES PATENTS 6/1959 Langdon et a1 19/156.3 X

AIR

3,641,627 2/1972 Lee et a1 19/156.3

FOREIGN PATENTS OR APPLICATIONS 1,017,042 9/1952 France 19/89 1,172,561 10/1958 France 19/89 703,376 2/1954 Great Britain 19/89 Primary ExaminerDorsey Newton Attorney-John F. Ryan [5 7] ABSTRACT By adjusting the flow of air into the beater chamber of a picker lapper so that more air is delivered to the sidewall sections than to the center of the chamber, laps of textile fibers are produced which are heavier in the center sections than at their edge sections.

2 Claims, 7 Drawing Figures Patented Oct. 16, 1973 4 Sheets-Sheet 1 AIR FIG. I

Patented Oct. 16, 1973 4 Sheets-Sheet 2 OOOOOO0OOooo.oooo o o 0 V 0 0 o 0 600 000 oo oooooooooooooo APPARATUS FOR ALTERING WEIGHT PROFILE OF PICKER LAPS This invention relates to a process and device for changing the weight profile of picker laps comprising textile fibers. More particularly, it relates to a process and device whereby picker laps can be produced which are heavier per unit of area in the center section of the lap than they are at the edge sections.

BACKGROUND In the preparation of carded webs of textile fibers such as cotton fibers, rayon, acetate, and other natural or synthetic fibers, a carding machine of the flat-top or roller-top type is conventionally fed at its input end by clumps of fibers pulled out of a feed roll known as a lap or picker lap.

Such laps consist of a rolled up array of fibrous clumps or aggregates. Weighing generally from 12 to 20 ounces per square yard, they are formed in a machine known as a picker lapper, the picker lapper being a device which by various conventional means removes fibers from a hopper feeder and blows them into a continuous compacted coarse-grained mat or batt.

It is a recognized characteristic of most picker lappers that the lap of fibers produced is normally some 5 to percent heavier in weight in each outer third of the width of the lap than it is in the center third. A typical weight analysis of such laps will show that, with feeds set to deliver a ounce per square yard lap, the weight will be 20 ounces at the outside edges, but the weight profile will be concave downward, decreasing to 19 ounces or less per square yard in the center.

Since carded fleeces even from laps with uniform weight profile tend to be somewhat heavier at the edges than in the center, the use of laps with heavy edges exaggerates the heavy edge profile of the carded fleeces.

This variance is not particularly disadvantageous when several card fleeces are plied together, as in the manufacture of nonwoven fabrics where the width of the finished'nonwoven fabric is to be the width of the card fleece as delivered from the card. However, in order to meet the commercial demands for nonwoven fabrics which are 60 or 80 inches wide, it is a recognized practice to employ standard carding machines, 40 inches wide, and to stretch laterally the fleeces from a number of such machines, to the desired width. Such 40 inch cards are readily available, are inexpensive compared with wide-width cards, and take up less room than wide cards.

It is common practice, therefore, to deliver a plurality of 40 inch card fleeces to one or another of the stretching devices known as web spreaders'. These conventionally consist of elastic bands or covered springs which are caused to stretch laterally while the card fleeceslay in contact with the expanding member, so that the card fleeces are caused to expand in width as they pass through the spreader. By such devices, 40 inch wide card fleeces can be increased in width by 50 to 100 percent or more.

It has been found, however, that particularly in the case of web spreaders which do not have positive control over the card fleeces, and where the spreading force is due only to the face-to-face contact of the expanding members with the card fleeces, the fleeces do not expand laterally in a uniform fashion. The center portion of such expanded fleeces is customarily even lighter in weight, proportionately, than would be predicted from the weight profile of the picker laps from which the fleeces were produced. Due to this sort of disproportionation, it is not unusual to find that picker laps which are 10 percent lighter in weight in the center than at the edges will result in fleeces which, when stretched percent in width by a conventional web spreader, are 30 percent heavier in their outer onethird portions than in their center third.

In order to counteract this defect, it is desirable to devise a method whereby picker laps can be made which are heavier in the center than at the edges. It is a primary object of this invention to provide such a method, and an apparatus therefor.

It is an additional object of the invention to provide a method of producing picker laps which, when carded into fleeces, will yield fleeces which when stretched will not show more than 10 percent average variation in weight between the center one-third section and the outer one-third sections.

TECHNICAL DISCLOSURE The invention will be better understood from the following description and drawings in which:

FIG. 1 is a side elevation of the beater section of a picker lapper, modified according to the process of this invention.

FIG. 2 is a front elevation of the modifying device of this invention.

FIG. 3' is a side elevation of the device of FIG. 2.

FIG. 4 is a weight profile of a conventional prior art picker lap.

FIG. 5 is a weight profile of card fleeces made from the picker laps of FIG. 4 and then stretched laterally to 225 percent of their original width.

FIG. 6 is a weight profile of a picker lap made according to the process of this invention.

- FIG. 7 is a weight profile of card fleeces'rnade from the picker laps of FIG. 6 and then stretched laterally to 225 percent of their original width.

The basis of the present invention is as follows.

As explained in more detail below, one essential element of a picker lapper is a beater device, completely enclosed, which receives a feed supply of partially opened fibers and performs the final opening operation, forwarding the fibers to be condensed on a moving screen or screens whence they are rolled up in lap form. Mounted below the beater arms and in close proximity to the surface of rotation of the arms is a curved set of adjustable grid bars through which air passes up into the beater chamber.

It has now been found, surprisingly, that if the profile of the volume of air passing through the grid bars and into the beater chamber is changedfrom a uniform flow to a profile in which more air flows into the outside or sidewall areas of the chamber than flows into the central portion of the chamber, the resulting fiber laps are heavier in their center portion than at their edges. The reason for this is not exactly understood, since it would be presumed that a larger volume of air at the edges of the chamber would act so as to entrain and deposit more fibers in that area. The exact opposite, however, has been found to be true.

Referring to FIG. 1, there is shown a portion of the beater section of a picker lapper, comprising a beater l2 enclosed in a housing 10. The type shown, mounted on shaft 13, is provided with three arms, 14, with teeth or points 16 on their outer surfaces. A batt of fibers, not shown, is fed to the beater chamber between feed plate 28 and feed roll 30, the rate of feed being controlled, if desired, by a sensing device 32.

The rotation of the beater arms impels fibers out of the chamber and into the chute 27, whence they are condensed on a screen, not shown.

Beneath the surface of rotation of the beater arms is a set of horizontal grids 18, mounted above the grid bar chamber 22. Air, circulated by fans or blowers, in part enters the beater chamber from below through the grid bars and associated chamber, and in part at the outer throat of the beater chamber through the closed duct 24, as shown. The portion of the air passing into the outer throat of the beater chamber through the duct 24 may be accelerated by the optional projection 34 on the duct wall 35, which narrows the duct at its upper outlet in a Venturi-like fashion.

The above details, though helpful in understanding the instant invention, are conventional and are found in one or more of the commercially available picker lappers. They are not claimed as part of this invention.

In order to make laps which are heavier in the center than at the edges, as set forth above, the volume of air entering into the beater chamber from below is increased at the sidewall portions of the chamber and decreased toward the center. One method of accomplishing this would be to replace the horizontally-disposed adjustable grid bars 18 with grid bars which are curved vertically downward, and adjust the grid bars so that maximum air is allowed to pass through the bars near the side walls of the beater chamber, with less air being delivered to the center. Another method is to supply more air to the side-wall sections by means of auxiliary blowers with fishtail outlets.

It has been found that a third expedient, depicted herein, provides a simple, inexpensive, and easily installed solution to the problem. A rigid perforated masking shield shown at 20 in FIG. 1, in front elevation in FIG. 2, and in side elevation in FIG. 3, is mounted in rather close proximity to the curved grid bars, being normally spaced V4 inch or less therefrom and conforming to the curvature of the grid bar section. This shield is hingedly mounted at the lower wall of the grid bar chamber, and substantially encloses the chamber from upper wall to front lip and from side wall to side wall.

As shown in FIG. 2, this shield is perforated with a series of holes only a few of which are shown, and the holes are larger at the outer edges of the shield, diminishing in diameter as they approach the center. A convenient but not restrictive set of dimensions for these holes, using a shield 39 inches wide and made of 1/16 inch thick stainless steel, would be a set of three holes (23) seven sixteenth inches in diameter, spaced one inch on centers and extending substantially from the bottom edge to the top edge of the shield. This is succeeded, proceeding toward the center of the shield, by vertical rows of three holes of three-eighths inch, fivesixteenths inch, one-fourth inch, three-sixteenths inch, one-eighth inch, and one-sixteenth inch (25) in diameter, all holes being one inch on center. The rows of holes then gradually enlarge, in similar manner, to the opposite outer edge of. the shield. The shield is attached 6 and that numerous other arrangements or methods of increasing the air volume at the walls of the beater chamber will readily suggest themselves to those skilled in the art.

APPLICATION OF THE PROCESS FIGS. 4 and 5 represent, respectively, the weight profiles ofa typical prior art lap, 39 inches wide, in ounces per square yard, and of an assembly of sixsuperimposed card fleeces, carded from such prior art laps at an original 40 inch width and then stretched to inches in width on a web stretcher. The weight of the stretched card fleeces is expressed in grams per square yard.

It will be readily apparent that although the original laps were only 5 percent lighter in the center than at the edges, the weight profile of the resultant stretched fleeces was grossly distorted, showing heavy edges (40 percent heavier than the average weight across the fleece) and light in the center (18 percent lighter than the average weight). A summation of all the deviations from the average fleece weight, taken at all measuring points, indicated that the average deviation at any measuring point is 17 percent from the average fleece weight.

One of the principal uses of such stretched fleeces is for further processing, by the use of a polymeric binder, into wide nonwoven fabrics. With erratic weight profiles such as shown in FIG. 5, the whole overall weight of the nonwoven fabric must be increased in order that the lightest portions of the fabric will meet the minimum tensile strength requirements, which is an uneconomic and wasteful procedure.

FIG. 6 is a weight profile of picker laps of the same fiber composition as in FIG. 4, the only process variable being the installation of the perforated shield of FIGS. 2 and 3 in the position shown in FIG. 1, as set forth above. The laps average 13 percent heavier in the center than at the edge portions.

The picker laps of weight profile as shown in FIG. 6 were carded into 40 inch wide fleeces, six of which were plied together and stretched to 90 inches in width by the same web spreading mechanism as used above. The resulting weight profile of the stretched fleeces is shown in FIG. 7, where the maximum weight deviation from the average fleece weight is 19 percent, and the average deviation, taken at all measuring points, is less than 7 percent from the average weight of the stretched fleeces. Fleeces of such improved lateral weight uniformity offer obvious economies in the production of bonded nonwoven fabrics.

Having thus described our invention, we claim: I

1. In a substantially enclosed beater section of a picker lap machine which comprises a set of rotating arms forming a rotating beater device describing a surface of rotation and means for supplying air from below to said beater section, that improvement which comprises means for supplying to the outside edges of said surface of rotation of said rotating beater device a larger volume of air than is supplied to the center section of said surface of rotation,

said means comprising a curved masking shield substantially enclosing the area from which-air is delivered from below to said heater section,

said shield containing a plurality of openings therein,

said openings being larger at the outer edges of said shield than at the center portion of said shield,

the openings in said masking shield comprise a series of holes which are larger in area at the outer edges of said shield than at the center portion of said shield. 

1. In a substantially enclosed beater section of a picker lap machine which comprises a set of rotating arms forming a rotating beater device describing a surface of rotation and means for supplying air from below to said beater section, that improvement which comprises means for supplying to the outside edges of said surface of rotation of said rotating beater device a larger volume of air than is supplied to the center section of said surface of rotation, said means comprising a curved masking shield substantially enclosing the area from which air is delivered from below to said heater section, said shield containing a plurality of openings therein, said openings being larger at the outer edges of said shield than at the center portion of said shield, and said shield being curved in a radius generally corresponding to the radius of curvature of the surface of rotation of said beater device.
 2. The improvement according to claim 1 wherein the openings in said masking shield comprise a series of holes which are larger in area at the outer edges of said shield than at the center portion of said shield. 